Hi
Ive never really painted PLA before until now, and it’s apparent that painting acrylics without primer is not going to work 
. However, I really like the look and ease of just using the PLAs filament colour as is, but sometime would need to paint the odd detail on top - eg. eyes etc.
Is there a paint like (oil paint for example) that would be able to be painted straight onto PLA?
thanks for any advice!
Nick
Actually, I did use acrylics on PLA in the past to very good effect. At least for visual exhibition pieces so not much handling.
Nevertheless, acrylics such as the Revel range of model paints do work on PLA for this purpose.
Oh! Was that without priming first? When I painted without prining it didn’t seem to adhere at all! 
Exactly. Years ago, I got a couple of fairly elaborate scaled prototypes for work and pimped them by sanding the surfaces to a nice finish, painting with the Revel acrylic colors (not the water based colors though) and applying decals which I had printed out. Still looking great 
Since you mentioned the Eyes:
Nowadays, with the AMS and a second one underway, I do quite enjoy doing the painting in Studio. Lots of poop of course, but it is quite fun to see what current printers can do. My Avatar is a 200% Cults print painted in Studio and printed in PETG.
I didn’t get the ams as didn’t want the extra time and waste (and am planning to paint more really).
So the acrylics you used weren’t water based? Would you mind sharing? Mine are valeo acrylics so maybe not the best
I have used the Revell emaille colors for decades to (mainly) very good effect. There’s a bunch of them available. One example on Amazon is ASIN B00ITPWUBA but there are plenty more.
I have also used their range of Aqua Colors with slightly more mixed results but I am afraid that I can not remember if I have used them on the PLA prints.
In my memory, they do require a good mix with a couple of toothpicks prior to use.
Also, I have always used several thin coats as these give better performance (both optically and mechanically) than a single thick coat. But that goes for all painting.
These are not acrylics, they’re enamel paints, and they’ll stick to anything, and are quite sturdy. However they’re not solvent free, but they dry quicker than oils.
@Jon mentioned in another thread that PLA will soften a bit when exposed to acetone which gives a handle on getting things to stick to the surface.
It’s been a long time but I think model paints used to be thinned with acetone. Just checked the MSDS for Revell paint thinner and it’s a mix of 2-butanone and 2-Methoxy-1-methylethylacetate.
2-butanone is somewhat similar to acetone. I can see Revell paints possibly working on PLA (even more with @EnoTheThracian’s personal experience!).
One thing I did for a project was print a model in Bambu matte PLA and then painted it with thick superglue. (thin may work just as well) I was surprised how well it flowed and it left me with a surface I think was all ready for paint if I had wanted to paint it. If Revell paints don’t work as hoped, it might be worth painting a test piece with superglue to see if that makes a fair base for paint?